NSW Premier Gladys Berejiklian has announced the new measures gyms must take, including having a COVID-19 safety plan in place and a staff member on shift at all times to monitor hygiene and social distancing.

Wagga independent gym owner Ashley Warren said the new rules would be a challenge because of the cost associated with rostering on a hygiene marshall.

"It's not ideal, at a time when we've earned no money for three months and we've only had the doors reopened for a month," Mr Warren said.

"Now we're going to have to double our wage bill, or an owner like me will have to work 70 or 80 hours a week to try to give the members time to train."

Mr Warren, whose Flexit Gym usually opens as early as 4am and closes late at night, said he was "upset for all the gym owners and gym people out there".

"I'm gutted for everybody that's put in so much effort and, of course, for the wider industry, we really don't need this at the moment," he said.

NSW Health's Dr Jeremy McAnulty said the state was "at a knife's edge" in controlling the virus.

Dr McAnulty said there were more than 18,000 people tested in the 24 hours to 8pm on Tuesday and the state had now recorded 3529 COVID-19 cases since the start of the pandemic.

Nineteen new cases of coronavirus had been found in NSW in the past 24 hours, with two of those identified in overseas travellers.

NSW Minister for Customer Service Victor Dominello said the state could not afford to take any risks "or allow complacency to creep in".

"Businesses must take all reasonable steps to reduce the risk of COVID transmission or risk facing a fine or closure," Mr Dominello said.

"Gyms play a crucial role in the promotion of health and fitness across our community, but they are not immune from this challenge."

Mr Warren said it was important for people to be able to exercise as a way to counteract the mental stress of the pandemic.

"Ninety-five per cent of people now train for mental health first, and the good body second. The good body comes as part of coming to the gym for your mental health," he said.

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